13C MAS NMR investigations of alkali doped C60

Results of13C MAS NMR measurements of the Rb x C60 system (x=2.75, 3, 4, 6) and the A6C60 compounds (A=K, Rb, Cs) are presented. Special attention was paid to sample preparation in order to suppress effects of impurities and lattice defects due to imperfect C60 starting material. The13C MAS NMR measurements of the Rb x C60 system demonstrate the usefulness of this method to reveal valuable information about its phase diagram. The existence of underdoped Rb3C60 is proved. Well resolved lines in all investigated A6C60 compounds confirm the orientational order of the C60 ions. An assignment of the signals to the three magnetically inequivalent carbon atom positions in the crystal structure is proposed.